BACKGROUNDSodium 4-phenylbutanoate (NaPB) can induce cellular differentiation and cell cycle arrest. However, its potential anticancer properties in hepatocellular carcinoma and influence on normal liver cell are still unclear. We observed the effects of NaPB on growth inhibition, including differentiation and phase growth arrest in normal liver cell line L-02 and hepatocellular carcinoma cell line Bel-7402. Furthermore, we investigated its mechanism in Bel-7402. METHODS; Hepatocellular carcinoma cells Bel-7402 and normal liver cell line L-02 were treated with NaPB at different concentrations. Light microscopy was used to find morphological change in cells. Cell cycle was detected by flow cytometry. Expression of acetylating histone H4 and of histones deacetylase 4 (HDAC4) were determined by Western blot. The expression of P21WAF1/CIP1 and E-cadherin were observed through immunocytochemistry.

RESULTSNaPB treatment led to time dependent growth inhibition in hepatocellular carcinoma cells Bel-7402. NaPB treatment caused a significant decline in the fraction of S phase cells and a significant increase in G0/G1 cells. NaPB increased the expression of P21(WAF1/CIP1) and E-cadherin in Bel-7402 and significantly decreased the level of HDAC4 in Bel-7402. NaPB significantly improved the level of acetylating histone H4. The normal liver cell line L-02 showed no distinct changes under treatment with NaPB.

CONCLUSIONSNaPB inhibited the growth of hepatocellular carcinoma cells Bel-7402 and induced partial differentiation through enhancing the acetylating histones. In Bel-7402, the expressions of P21(WAF1/CIP1) and E-cadherin may be related to level of acetylating histones and inhibition of cellular growth. NaPB showed no significant effect on normal liver cells.